Some very important things can be extracted from this: For starters, the simple fact of having a snapshot to a VM means that all ROPS of this VM grow with a factor 2 (!). On top of that, when the VM writes a block that was not written to the snapshot before you also need twice the WOPS on that VM. This is due to the fact that VMware has to update the table of “where to find what block” (snapshot or base disk). This impacts performance significantly!